1. Field of the Invention
The present invention relates to a method of restarting a loom which is stopped upon the occurrence of faulty picking or a loom stopping cause that requires stopping the loom.
2. Description of the Related Art
FIGS. 1 and 2 are diagrams of weaving cycles A, B and C in which conventional procedures of stopping a loom upon the occurrence of a loom stopping cause requiring stopping the loom, removing the loom stopping cause and restarting the loom, in relation with the angular position of the main shaft of the loom. FIG. 1 shows a procedure of stopping and restarting the loom when the loom is stopped due to faulty picking, and FIG. 2 shows a procedure of stopping and restarting the loom when the loom is stopped due to a loom stopping cause other than faulty picking.
Referring to FIGS. 1 and 2, a picking operation is carried out at an angular position of about 80° in the weaving cycle A, and a beating-up operation is completed at an angular position of 360° corresponding to an angular position of 0° in the weaving cycle B. When a fault is detected in the weaving cycle B and a stop signal is provided at an angular position of, for example, 290°, generally, the loom keeps operating for a braking period corresponding to about one turn of the main shaft, and the loom comes to an initial stop with the main shaft at an angular position of, for example, 260° in the weaving cycle C. Any picking operation is not carried out in the weaving cycle C subsequent to the weaving cycle B in which the loom stopping cause was detected. A shedding operation, a beating-up operation, a let-off operation and a take-up operation are carried out while the loom is being braked to stop the same.
Referring to FIG. 1, when a weft yarn is picked by faulty picking, a loom controller, not shown, reverses the loom at a low speed, stops the loom for an intermediate stop at an angular position of, for example, 180° in the weaving cycle B in which faulty picking occurred to remove a weft yarn picked by faulty picking. In this state, the weft yarn picked by faulty picking is removed by an operator or by an automatic weft extracting device. Subsequently, the loom is further reversed at a low speed and is stopped for a final stop at an angular position of, for example, 310° in the weaving cycle A preceding the weaving cycle B, and then the loom is restarted. When warp yarns need mending, the warp yarns are mended while the loom is at any one of the stops.
Referring to FIG. 2, if the loom is stopped in spite of successful picking, the intermediate stop is skipped, and the loom is reversed and stopped for the final stop at an angular position of, for example, 310° in the weaving cycle B preceding the weaving cycle C in which the loom was stopped for the initial stop, and then the loom is restarted. If the warp yarn needs mending, the warp yarns are mended at any one of the stops.
When the loom is reversed at a low speed in a period in which the weaving operations of the loom are stopped, the cloth fell of a fabric on the loom is beaten by a false beating-up operation and several weft yarns adjacent to the cloth fell are dislocated in the direction of the thickness of the fabric. As is generally known, a thick filling streak, i.e., a pillowlike protrusion extending across the fabric generally called “wavy set mark”, is liable to be formed if the loom is restarted with the weft yarns adjacent to the cloth fell dislocated in the direction of the thickness of the fabric. A false beating-up operation is repeated three times as shown in FIG. 1 when faulty picking occurs. A false beating-up operation is repeated twice as shown in FIG. 2 when the loom is not stopped due to faulty picking. The repetition of the false beating-up operation causes the defect called “wavy set mark”.
There is a known loom restarting method called “one-shot-picking” method as a means for preventing the defect called “wavy set mark”. As shown in FIG. 3, the one-shot picking method inserts one weft yarn after removing the weft yarn picked by faulty picking when the loom is at the position for the intermediate stop (FIG. 1), and then restarts the loom. Therefore, two false beating-up operations can be omitted, so that the formation of the defect called “wavy set mark” can be prevented.
However, when the loom is restarted by the one-shot-picking method, the weft yarn inserted into the shed at the restart of the loom cannot be beaten up properly because the main shaft is at an angular position of, for example, 180° where the warp is substantially in a maximum shed for picking, the rotating speed of the main shaft of the loom is unable to rise to a normal operating speed before the first beating-up operation after restarting and, consequently, a light filling bar is formed. Furthermore, the one-shot-picking method cannot be applied to restarting the loom when the loom is stopped due to a cause other than faulty picking.